i have the address how do i findout their name?

Answer 1

Is it likely to be a company or individual?

If individual, do a search on the voters list. If it is not an individual, eg company, firm or partnership check at local library to see if there is a street directory.

Answer 2

Depends on where you are. I use the Property Appraisers Web Site if they are an owner. If they rent that doesn't work.
Most County Gov't operate this. Here is the starting point for the State of Florida